1. Field of the Invention
The present invention relates to a coating film forming apparatus and a coating film forming method for coating, for example, a semiconductor wafer, and a processing substrate such as an LCD substrate, an exposure mask and the like with liquid, which is obtained by dissolving resin and so on, particularly a resist liquid to form a film of this liquid.
2. Description of the Related Art
A mask for forming a circuit pattern on a surface of a semiconductor wafer, and that of a processing substrate such as an LCD substrate and like is obtained by coating the substrate surface with a resist liquid, irradiating the resist surface with light, an electron beam, or an ion beam and developing the resultant. As a resist liquid coating method, a spin coating method is mainly used. This method, for example, as shown in FIG. 33, a substrate, e.g., a semiconductor wafer (hereinafter referred as xe2x80x9cwaferxe2x80x9d) W is absorbed and held on a spin chuck 11 having a vacuum absorbing function, a resist liquid 13 is dropped on the central portion of wafer W from a nozzle 12, thereafter, the wafer W is rotated at high speed, whereby diffusing the resist liquid 13 to the entirety of wafer W by a rotational centrifugal force, so that a substantially uniform resist film is formed over the entire surface of wafer W.
There has been a growing trend in recent years to fine the wiring width of the circuit pattern, and it is required that a resist film be thinned since the wiring width of the circuit is proportional to the thickness of the resist film and an exposure wavelength. In the spin coating method, an increase in the rotational speed of wafer W allows the resist film to be thinned. For this reason, for example, 8-inch wafer W is rotated at high speed of 200 to 4000 rpm.
However, this spin coating method has the following problems to be solved.
First, according to this method, when the wafer W is upsized, peripheral speed at an outer peripheral portion is increased, so that air turbulence is generated. The thickness of resist film is easily varied by this air turbulence to reduce uniformity of the resist film thickness, and this causes a reduction in exposure resolution. For this reason, it is difficult to obtain a fixed coating thickness in the case of the film thickness of 0.4 xcexcm or less, and there is a limitation in the manufacture of about more than some giga-semiconductors naturally.
Next, according to this method, in the process in which the resist liquid is spread to the peripheral edge portion from the central portion of wafer W, solvents contained in the resist liquid are sequentially evaporated. This makes a difference in viscosity of the resist liquid along the diffusion direction, to cause a possibility that the thickness of resist film formed between the central portion and the peripheral edge portion will differ.
Moreover, according to this method, since the wafer W is rotated at high speed, the amount of resist liquid, which is spread from the peripheral edge portion of wafer W and becomes useless, is large. As one example, it is clear that only 10% or less of the amount of resist liquid supplied onto the wafer W contributes to formation of resist liquid film.
Furthermore, though there is a necessity to rotate the wafer W in a cup to receive the splashing resist liquid, there is a possibility that the resist liquid adhered onto the cup will form particles with which the wafer W will be polluted. For this reason, the cup must be frequently cleaned.
Still furthermore, according to this method, the outside area of the circuit forming area of wafer W is also coated with the resist liquid. If the resist liquid is left in this area, this will cause occurrence of particles in the later process. For this reason, the resist liquid of this area must be removed by a dedicated device, which is called edge remover, just after the resist liquid coating process.
As a method in place of the aforementioned spin coating method, the inventors of this invention have reviewed the following method (hereinafter referred to as xe2x80x9cone-stroke drawing typexe2x80x9d):
Specifically, as shown by a solid line in FIG. 34, the nozzle 12 for discharging the resist liquid 13 onto the surface of wafer W and the wafer W are relatively reciprocated in an X direction as being intermittently feeding by a predetermined pitch in a Y direction to coat the wafer W with the resist liquid in the so-called one-stroke drawing manner. In this case, it is preferable that the portion other than the circuit forming area of wafer W be covered with a mask in order to prevent the resist liquid from being adhered onto the peripheral edge of wafer W and the rear surface. In this method, since the wafer W is not rotated, the aforementioned problems are solved and the resist-liquid coating can be performed without wasting the resist liquid.
In the coating method of the one-stroke drawing type, a diameter of a discharge hole of the nozzle 12 is formed considerably thinly, that is, about 10 xcexcm to 200 xcexcm in order to reduce the thickness of the resist film. When the resist liquid 13 is discharged from the nozzle 12 and collides with the wafer 12, the resist liquid 13 expands wider than the discharge diameter as shown in, for example, FIG. 35, with the result that the discharged resist liquids 13 are connected to one another and a liquid film of the resist liquid 13 is formed on the entirety of the surface of the wafer W.
However, when the coating of the resist liquid 13 is made from a coating start point, which is shown by Ya in FIG. 36, to a coating end point, which is shown by Yb, in a direction shown by an arrow in the figure, there is confirmed occurrence of a phenomenon in which the film thickness at point Ya becomes larger than the film thickness at point Yb. Depending on the kind of resist liquid 13, the film thickness at point Ya becomes conspicuously high in some cases.
The reason can be considered as follows:
Specifically, the resist liquid 13 is drawn to the pre-coated area shown by slanted lines of FIG. 20 by the above-mentioned expansion of the resist liquid 13, which is caused by the collision with the wafer W. In this way, the film thickness at point Ya becomes large.
While, in order to obtain a necessary film thickness, parameters such as a discharge quantity of resist liquid, discharge pressure, scanning speed of coating liquid nozzle (moving rate in an X direction), an index pitch (intermittent moving distance) of wafer W, and so on are appropriately set, coating of resist liquid is performed on the condition, and drying is performed, and then the thickness of the resist film is measured. Then, the discharge pressure is controlled based on the measurement result. However, the work for controlling the parameters by trial and error is cumbersome. In addition, when the solid content quantity in the resist liquid varies, the amount of solvent, which is volatilized and disappears, varies even if the coating with the same amount is carried out, with the result that the film thickness of the resist is changed. Moreover, the range for changing the values of the respective parameters is determined to some degree in accordance with hardware configuration. For this reason, regarding a case in which the film thickness is doubled, it is impossible to deal with such a case by a method in a value of one parameter is simply doubled. Namely, the plurality of parameters must be controlled. For the above-mentioned reason, a so-called condition derivation work is complicated and needs much time, causing a problem in which smooth activation of the apparatus is prevented.
It is an object of the present invention is to provide a coating film forming apparatus, which is capable of obtaining a stable film thickness over a substrate surface by dividing a coating area of the substrate, and relates to a coating film forming method.
Another object of the present invention is to provide a coating film forming apparatus, which is capable of forming a coating film with a high yield of coating liquid and uniformity, and which is capable of easily performing a parameter value setting work for obtaining a necessary film thickness, and to provide a coating film forming method.
In order to attain the above objects, according to the present invention, there is provided a substrate holding section for holding a substrate substantially horizontally; a supply nozzle for supplying treatment solution to a surface of the substrate held by the substrate holding section; a driving mechanism for relatively driving the substrate holding section and the supply nozzle along a substrate surface direction; and a control section for controlling an operation of the driving mechanism, wherein the control section controls the operation of the substrate holding section and/or the supply nozzle through the driving mechanism to supply the treatment solution to each of divided coating regions of the substrate in a predetermined coating order and/or a predetermined coating direction, and controls timing at which the treatment solution is supplied to the substrate from the supply nozzle, whereby forming a liquid film of the treatment solution for each divided region of the substrate surface.
Moreover, according to the present invention, there is provided a coating film forming apparatus comprising the steps of supplying a treatment solution to a first region on a substrate, which is divided into at least first and second regions, as relatively moving the substrate and a supply nozzle for supplying the treatment solution onto the substrate along a substrate surface direction; and supplying the treatment solution to the second region as relatively moving the substrate such that a coating start position is nonadjacent to a coating end position in the supply step of the first region.
According to the above structure, the phenomenon, in which the resist liquid is drawn to the coating start position, so as to increase the film thickness of the portion, occurs in only the corresponding region. The amount of treatment solution, which is drawn to the coating start position, is small in the corresponding region. Though the film thickness at the coating start position is large, the degree thereof is considerably relaxed as compared with the case in which the coating area of the substrate is not divided. Resultantly, uniformity of the inner surface of the film thickness can be improved.
Regarding the control section, if the coating start points of the adjacent divided regions are next to each other, the amount of treatment solution, which is drawn to the boundary portion, is increased, so that and the film thickness of the corresponding portion is conspicuously increased. For this reason, it is desirable that the coating start points of the adjacent divided regions should not be next to each other. Moreover, if the coating is continuously performed in order of the coating end position and the coating start position when the coating end position of one region of adjacent divided regions and the coating start position of the other region are next to each other, these two regions are coated together. As a result, the treatment solution is drawn to the coating start position of the fist coating region, and the film thickness of this portion is increased. In this case, it is desirable that the coating should not be continuously performed in order of the coating end position and the coating start position.
The driving mechanism may have the structure in which the driving mechanism relatively moves the supply nozzle and the substrate holding section in a direction substantially orthogonal to one side of a circuit forming area of the substrate as being intermittently fed at a predetermined pitch in a direction substantially parallel to the one side of the circuit forming area.
In this case, the driving mechanism may be structured such that the supply nozzle and the substrate holding section are relatively rotated about a vertical axis and the control section may be structured to perform such control through the driving mechanism that the supply nozzle and the substrate holding section are relatively rotated about a vertical axis before moving the supply nozzle and the substrate holding section, which are placed at a coating end position of the divided region, to a coating start position of the divided region to be next coated. In this case, the coating direction and the moving direction of the supply nozzle can be aligned, whereby allowing the coating to be performed in the set coating order and coating direction.
Moreover, the driving mechanism may have the structure in which the driving mechanism relatively moves the supply nozzle and the substrate holding section as if a spiral were drawn on the surface of the substrate held by the substrate holding section. As an example of the treatment solution, the resist liquid can be named.
Furthermore, according to the present invention, there is provided a coating film forming apparatus comprising a substrate holding section for holding a substrate; a supply nozzle, which is disposed to be opposite to the substrate held by the substrate holding section, for discharging treatment solution to the corresponding substrate; a treatment solution supply control section for controlling discharge of the treatment solution from the supply nozzle; an X-direction driving mechanism for moving the supply nozzle in an X direction; a Y-direction driving mechanism for relatively moving the substrate holding section and the supply nozzle intermittently in a Y direction; a parameter setting section for partially designating parameters values, which are processing conditions for applying the coating of treatment solution to the substrate by the supply nozzle, to set a residual parameter value; and processing means for generating a control signal for controlling the supply control section, X-direction driving mechanism, and Y-direction driving condition based on the parameter value set by the parameter setting section, wherein the corresponding supply nozzle is moved in the X direction as discharging the treatment solution from the supply nozzle in a state that the substrate holding section is stopped, and then the substrate holding section and the supply nozzle are relatively moved in the Y direction, and this operation is repeated, whereby applying the treatment solution to an entire surface of a coating film forming area of the substrate.
Still furthermore, according to the present invention, there is provided a coating film forming method comprising the step of partially designating parameters values, which are processing conditions at the time of supplying a treatment solution to a substrate, to set a residual parameter value; and supplying the treatment solution onto the substrate based on the set parameter values as relatively moving a supply nozzle for supplying the treatment solution onto the substrate and the held substrate.
In this invention, the treatment solution is applied to the substrate as discharging the treatment solution in the form of a line with a thin diameter. The partial parameter values are any two of a scanning speed, which is a moving speed of the supply nozzle in the X direction, a pitch, which is a relative intermittent moving distance of the substrate in the Y direction with respect to the supply nozzle, and either one of discharge pressure and a discharge flow rate of the treatment solution of the supply nozzle, and the residual parameter value is one of these residual parameter values.
The parameter setting section comprises a first storage section, which stores the relationship between the discharge pressure and the discharge flow rate of the treatment solution in accordance with a diameter hole of the supply nozzle and a solid content quantity of the treatment solution, and a target film thickness of the coating film and a solid content quantity of the treatment solution are designated, and there is provided a function of designating two of the scanning speed, pitch, and discharge pressure, whereby obtaining one residual value among the scanning speed, pitch, discharge pressure based on these designated values and data stored in the storage section. Also, the parameter setting section comprises a display section for displaying the designated parameter values and the obtained parameter value.
According to the aforementioned invention, it is possible to obtain the coating film with high uniformity of the inner surface of the film thickness as compared with the spin coating method. Moreover, there is substantially no waste of coating liquid, and the yield of coating liquid is improved. Then, even if all parameters are not set, the combinations of parameters corresponding to the target film thickness can be automatically attained, by setting only a part of parameters, so that the condition derivation of film thickness is easily carried out.
In the above invention, it is preferable that the parameter setting section should correct the parameter value based on the measured film thickness, which is actually obtained by the set parameter values, and the target film thickness. In this case, the condition derivation of film thickness is more easily carried out.
Furthermore, according to another invention, there is provided a coating film forming apparatus comprising a substrate holding section for holding a substrate; a supply nozzle, which is disposed to be opposite to the substrate held by the substrate holding section, for discharging treatment solution to the corresponding substrate; a treatment solution supply control section for controlling discharge of the treatment solution from the supply nozzle; an X-direction driving mechanism for moving the supply nozzle in an X direction; a Y-direction driving mechanism for relatively moving the substrate holding section and the supply nozzle intermittently in a Y direction; a parameter setting section for setting parameter values, which are processing conditions for applying the coating of treatment solution to the substrate by the supply nozzle, to correct the parameter values based on a measured film thickness, which is actually obtained by the set parameter values, and a target film thickness; and processing means for generating a control signal for controlling the supply control section, X-direction driving mechanism, and Y-direction driving condition based on the parameter value set by the parameter setting section, wherein the corresponding supply nozzle is moved in the X direction as discharging the treatment solution from the supply nozzle in a state that the substrate holding section is stopped, and then the substrate holding section and the supply nozzle are relatively moved in the Y direction, and this operation is repeated, whereby applying the treatment solution to an entire surface of a coating film forming area of the substrate.
These objects, other objects and advantages of the present invention will become readily apparent by the following description and the accompanying drawings.